/*  Copyright (c) 2011, Philip Busch <vzxwco@gmail.com>
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *   - Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */


#include <stdio.h>
#include <stdlib.h>
#include "id.h"

static int *ids;
static int numids;


int id_acquire(void)
{
	int i;
	int *tmp;

	// free slot available?
	for (i = 0; i < numids; i++) {
		if (ids[i] == 0) {
			ids[i] = 1;
			return i;
		}
	}

	// no: add slot
	tmp = realloc(ids, (numids + 1) * sizeof(*ids));
	if (tmp == NULL)
		return -1;

	ids = tmp;
	++numids;

	ids[numids - 1] = 1;

	return numids - 1;
}

void id_revoke(int id)
{
	int i;

	if ((id < 0) || (id >= numids))
		return;

	ids[id] = 0;

	if (id == numids - 1) {
		for (i = id; i >= 0; i--)
			if (ids[i])
				break;

		numids = i+1;
		ids = realloc(ids, numids * sizeof(*ids));
	}
}

void id_destroy(void)
{
	free(ids);
	ids = NULL;
	numids = 0;
}

